1. Field of the Invention
The present invention relates to a display system, and more particularly, to a display system disposing a charge pump circuit on a flexible printed circuit (FPC) externally coupled to its display device for improving its voltage converting efficiency.
2. Description of the Prior Art
In traditional small-sized and medium-sized thin-film transistor liquid crystal display (TFT-LCD) devices, with the growing size of the screen, the current consumption is also growing. At this time, if the charge pump circuit is disposed in the driving circuit of the TFT-LCD device, its voltage converting efficiency will be getting worse due to being limited by the indium tin oxide (ITO) resistors.
In addition, since the system end hopes to provide an input voltage ranging from 2.0V to 4.8V to the driving circuit of the TFT-LCD device directly, so the charge pump circuit shall be able to support a voltage converting ratio with different multiples (such as 1.5 times, 2 times, or 3 times) to provide the desired output voltage. If the charge pump circuit is moved from the driving circuit of the TFT-LCD device to a flexible printed circuit (FPC), it is necessary to consider how to control operations of the charge pump circuit on the FPC.